Process of refining impure lead bullion



Patented Sept. 19, 1933 I UNITED STATES OFFICE PROCESS OF REFININGIMPURE LEAD James 0. Johnathan Chicago, l nd eassignor to The Gliddei1Ccmpany, Cle,vela'nd,' Ohio, at corporation of Ohio No Drawing.Application February 193 1 1 t Y Serial N0. 515,893. I, 7 G1aims. (01.23- 69,)

This invention relates to a processifor recovto litharge or red lead bydecomposition with ering lead from lead-bearing materials or alloys heatby any of theWell-known methods. 1 consisting for the most-part of lead,but having i To obtain metallic pig lead, the filter cake may arelatively small amount of other materials, be fedto a' blast furnaceoranyother suitable} 5 such as antimony, arsenic, copper, bismuth,silsmelting furnaca'andsmelted according to exist-'- ver etc. Suchanalloy may be the crude bullion ing approved practice. 'The'gasirom'th'e blast resulting from the treatment of ores', or the furnace-may' be used asra source of-- carbon metal resulting from the smelting.of battery dioiiide gas and when the product is-to be made lead andmiscellaneous lead-bearing materials. altogether into pig'lead, itwill'not be' necessary 10 The purpose of the process is to obtain thelead to "scrub the gas "beiore goin'g to the carbonain the form ofsubstantially pure metallic lead, tion apparatus.,-,It is" unnecessary'to 'drythe orsubstantially pure lead product, such as white .filtercake before iti's 'fed to -the furnace and, lead, 'litharge, or redlead, :or with only Very when desired, thefilter'cake may lee-used as aslight amounts of other materials. souice ofmaterial for other leadcompounds! 15 As an example ofthe procedure in treating a Atypicalillustration -oi' the practice of the lead alloy according to myimproved process, process'wouldbe as'follows: j

the metal is first oxidized, and preferably atoma The metal is meltedand brought to-"a temized, in any suitable 'manner such as byappaperatureof about .-1000 'F.- It isvig'orouslyagi- 1 ratus used inthe manufacture of litharge from tated in'a current of air, by which theoxide is pure lead. It is advisable to leave some of the carried into asettling chamber. There willalso alloy unoxidized because, if anyimpurity gets be carried over with it some freemetal.

into the solution it may be removed by agitat-, One ton of this oxidizedmetal is leached with ing with powdered metallic lead and by leaving '20tons of solution containing 10% lead'acetatea small amount of,metalliclead in the oxidized It is "preferable tohave the'temperatureofthe f' materialthe complete removal'of the impurities solution over 100F, The amount of insoluble will be ensured. x residue will dependuponthe amount of impur- The oxidized mate'ial is then leachedin a itypresent, The insoluble will be filtered off. suitable leaching tank,with a solvent whichwill The clear solution-'of'basic acetate shouldthen:

. dissolve the lead oxide but which will leave the be treated withpurified COz'gas'." 1

3O impurities substantially undissolved. One such Assuming that of theweight-of the oxisolvent of suitable character for this purpose dizedmetal goes into solution,andisfreprecipi would be a more or less neutralsolution of lead tated'asa basic carbonate, the amount or caracetate.Whenthis solution isused, the-lead bonj as CO: that will be required totreat the r oxide goes into solution to .form a:basic lead solutionfrom'one'tonof oxidized metal-willbe acetate, and the impurities remainundissolved'. 58 pounds. However, the efiiciency'ofabsorp 9 or as aslime. v I tion of CO2 will probably be less than 50%.

The basic lead acetate solution, thus obtained, Instead of using'a. leadacetate solution for is then. treated with carbon dioxide gas whichleachingthe oxidized material, lead nitrate may may be in the form ofpurified flue gas or which I be used, or. a mixture, of the two. {Theslime may be derived from any other available source. and undissolvedimpurities resulting from the This precipitates the lead as a white leador a leaching operation may be treated by any suitcarbonate more or lessbasic. ,The treatment able methods to-recover the metals present withthe carbon dioxide gas is continued until therein, and the exact methodof treatment will 7 the lead acetate solution is restored to a subbelargelydetermined by the composition of-the 1 stantially neutralcondition and the precipitate slime and the impurities. I I

is then filtered off and the solution used again Having thus describedmy invention, I claim:

to treat a further portion of oxidized lead alloy.l 1. The steps or" thehereindescribed.process of When the final product that is desired iswhite recovering substantially pure lead compound,

lead, the flue gas must be scrubbed with water from ,an impureleadbullion containing other to remove sulphur and suspended matter. Themetals, which consist in first atomizing the buldegree of carbonationwill be regulated so as lion and oxidizing the major part thereof and toconform. to accepted standards of composi leaving a small. part thereofin .the 'metallic tion." state, then leaching the material thus formedThe carbonated compounds'thus obtained, as with a solution which willdissolve the lead oxthe precipitate or filter cake, may be converted idebut leavethe other oxides'contained in said material substantiallyundissolved, then removing the solids and slimes fromsaid solution andtreating the solution ,with'carbon dioxide to from a precipitate ofsubstantially pure lead carbonate and restore the leaching solution toits original condition, and filtering. said precipitate.

2. The steps of the hereindescribed process of recovering substantiallypure lead compound,

from an impure lead bullion containing other metals, which consist infirst atomizing the bullion and oxidizing the major part thereof andleaving a small part thereof in the metallic I state, then leaching thematerialthus, formed with a solution which will dissolve the lead oxidebut leave the other oxides contained in said material substantiallyundissolved, then removing the solids and slimesfrom said solution and"treating the soluti'on with, carbon dioxide to form a precipitate ofsubstantially pure lead carbonate and restore the leaching solution toits'original condition, filtering off said precipitate and usingtheregenerated leaching so1u-, tion, to treat another quantity of' saidoxidized material.

'3. .Thesteps of the hereindescribed process of recovering substantiallypure lead. compound, from an impure lead bullion containing othermetals, which consist in first oxidizing the major part ofthe bullionbut leaving asmall part unoxidized, then leaching the mixture ofoxidized an d unoxidized material thus formed a with asolution whichwill dissolve-the lead oxide but leave the other oxides as well" as fineunoxidized lead and metallic impurities precipitated by the lead,contained in said material,

substantially undissolved, then removing the solids and slimes from saidsolution and treating the solution with carbon dioxide to form aprecipitate of substantially pure leadcarbonate and regenerate theleaching solution, and filtering ofi said precipitates.

4. The steps or" the hereindescribed process of recovering substantiallypure lead compound, from an impure lead'bullion containing other metals,which consist in first oxidizing the major, part of the bullion butleaving 'a small 1 part unoxidized, then leaching the mixture ofoxidized and unoxidized material thus formed with a solution which willdissolve the lead oxide but leave the other oxides as well as fineunoxidized lead and metallic impurities precipir tatedby the lead,contained in said material,

substantially undissolved, j then removing the solids and .slimes fromsaid solution and treating the solution with-carbon-dioxide to form a'filtered solution.

a substantially neutral condition,

precipitate of substantially pure lead carbonate and regenerate the.leaching solution, filtering oflf said precipitate and using theregenerated leaching solution-to treatlanother quantity of said mixture.

5; The steps of the hereindescribed process of recovering substantiallypure lead compound,

from an impure lead bullion containing other metals, which consist infirst oxidizing the major part of the bullion and leavingv a small partof thebullion unoxidized, then leaching the mate rial thus formed with asubstantially neutral lead acetate solution to dissolve the lead oxideand form a, basic lead acetate solution, then removing the solids andslimes from said solution and treating the basic lead acetate solutionwith carbon. dioxide to form a lead 'corbonate precipitateandrestore-the lead acetate solution to a substantially neutral condition,and then filtering off said precipitate and treating another quantity ofsaid oxidized material with said 6. The steps of the hereindescribedprocess'of recovering substantially pure lead compound, from an impurelead bullion containing other I metals, which consist in, firstoxidizing the, major part of the bullion and leaving a small part of thebullion unoxidized,.then leaching the material thus formed with asubstantially neutral lead acetate solution to dissolve the lead oxideand form ,a basic leadzacetate solution, then removing. the solids andslimes from said solution from an impure'lead bullion containing othermetals, which consist in first partially oxidizing the bullion to form amixture, of oxidized and unoxidized material, then leaching the said mixturewith a substantially neutral lead nitrate solution .to dissolvethelead oxide but leave the other oxides as well as fine unoxidized leadand metallic impurities precipitated bythe lead and form a basic leadnitrate solution, then remov- 1 ing the solids and slimes from saidsolution and treating the basic lead nitrate solution with carbondioxide toforma lead carbonate precipitate and restore. the lead nitratesolution to a substantially neutral condition, and then filtering offsaid precipitate.

JAMES o. JOHNSTONE.

